Snoring is a common disorder which occurs in a variety of sleep-disordered breathing syndromes ranging in severity from simple snoring without apnea to upper airway resistance syndrome (UARS) and obstructive sleep apnea syndrome (OSAS) (Utley et al. (1997) Laryngoscope 107:726-734). A recent survey reported that 40% of the general population snore regularly (Ohayon et al. (1997) B.M.J. 314:860-863). Although social dysfunction often prompts snorers to seek treatment, even simple snoring without apnea is being increasingly recognized as having a negative effect on the snorer's well-being. For example, snoring disrupts sleep continuity, is associated with daytime sleepiness (Breslau et al. (1997) Am. J. Public Health 87:1649-1653; and Stradling et al. (1991) Thorax 46:807-810), and increases the risk of automobile accidents (Maycock (1996) J. Sleep Res. 5:229-37). Furthermore, non-apneic snoring has been implicated in the development of hypertension (Guilleminault et al. (1996) Chest 109:901-8; Lofaso et al. (1996) Chest 109:896-900). Also, regular snoring has been reported to be a significant risk factor for stroke (Spriggs et al. (1992) Neurol. Res. 14:94-96).
In recent years, treatment of snoring and sleep apnea by laser-assisted uvulopalatoplasty (LAUP) has become one of the most commonly performed medical laser procedures. The popularity of this procedure is believed to result, in part, from the prevalence of sleep-disordered breathing syndromes and by the fact that the procedure may be performed in an office setting with the patient under local anesthesia (Kamami (1994) J. Otolaryncol. 23:395-398; Hanada et al. (1996) Laryngoscope 106:1531-1533, Walker et al., (1995) Laryngoscope 105:938-943; and Wareing et al., (1996) J. Laryngol Otol. 110:232-236). LAUP was developed as a less radical alternative to uvulopalatopharyngoplasty (UPPP), a procedure in which oropharyngeal tissue is removed by surgical excision of excessive soft tissue that comprises the free margin of the soft palate, uvula, and lateral pharyngeal wall (Croft et al., (1990) Laryngol. Otol. 104:871-875; Friberg et al. (1995) Laryngoscope 105:519-522). UPPP typically is performed under general anesthesia. However, since both LAUP and UPPP rely on cutting the palate, neither is free from risk of impairing normal palate, and neither is free from risk of impairing normal palate function thereby allowing potential liquid regurgitation and hypernasal voice. Furthermore, postoperative pain apparently is severe for both UPPP and LAUP procedures.
In a new approach for treating snoring, a central longitudinal strip of mucosa is removed from the soft palate by use of a laser (Ellis et al. (1993) Ann. Roy. Coll. Surg. Engl. 75:296-290; and Ellis et al. (1994) Clin. Otolaryngol. 19:350-351). The objective of this procedure, also performed under general anesthesia but less radical than UPPP, is to induce fibrosis so as to stiffen the soft palate. Stiffening the soft palate may reduce snoring without the risk of impaired normal palate function associated with shortening the palate as in LAUP and UPPP. Air flow and vibration tests using a mechanical model simulating the palate and upper airway indicate that either shortening the palate or increasing its stiffness may be effective in relieving snoring (Ellis et al. (1994) supra). This hypothesis was supported by the elimination or significant reduction of snoring in 14 of 16 patients treated (Ellis et al. (1994) supra). Patients, however, reported severe soreness of the throat lasting about one week post-procedure. Longer term follow-up revealed some late failures (Ellis et al. (1994) supra), as has been the experience with UPPP. This procedure has also been modified by use of punctate monopolar electrocautery in non-apneic snorers (Whinney et al. (1995) J. Laryngol. Otol. 109:849-852). The procedure consists of, under general anesthesia, making ten to fifteen punctures of the soft palate and the palatal muscles diathermized on each puncture. At follow-up two to ten months after surgery, 18 of 21 patients reported improvement in snoring.
U.S. Pat. No. 5,674,191 discloses a method and apparatus for treating snoring using an ablation apparatus with a cannula for insertion of an energy delivery device into the soft palate and uvula. This method may be used to cause shrinkage and stiffening of the soft palate. The method may be used with the patient under local anesthesia, however, insertion of the energy delivery device into the tissues results in a wound on the tissue surface with the associated potential for pain and infection.
It is desirable to cause stiffening of the soft palate for treatment of simple snoring and other forms of sleep-disordered breathing in a manner that is non-invasive and leaves the tissue surface substantially intact, and which can be performed under local anesthesia.